While it's definitely a stretch, Kotaku Australia is offering up a couple of comparison screenshots suggesting that Titan Quest's portals served as inspiration for some of Diablo III's art. A sequel cloning a clone? I don't think so.
Raised stone platforms are pretty common architectural concepts, tho'.
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"No. They're all nuts, I'm just a guy in a shark suit." - Guy in a Shark Suit at Ron Paul rally, when asked if he was there to support Ron Paul